missing events in korganizer

Hi *,

today I realized, that korganizer is missing a few events from my nextcloud 
calendar.
All other clients can see them, including Evolution, DavX on Android, and even 
konsolekalendar (for example "konsolekalendar --view --date 2021-12-01") 
acting on the local Akonadi database is showing the events.
I removed the Akonadi database completely and recreated the nextcloud account, 
but the events don't show up. Akonadi is using a postgresql database.
I don't see any error messages in the Akonadi.log or in the system journal.

Any idea, what is going on here?

System is:

Operating System: openSUSE Tumbleweed 20211224
KDE Plasma Version: 5.23.4
KDE Frameworks Version: 5.89.0
Qt Version: 5.15.2
korganizer Version: 21.12.0-1.1
Kernel Version: 5.15.8-1-default (64-bit)
Graphics Platform: X11

TIA.

Bye.
Michael.